Purifying method and apparatus for gas-manufacturing



F. A. UMSTED. PURIFYING METHOD AND APPARATUS FOR GAS MANUFACTURING.

APPLICATION FILED FEB. 1.1918.

Patented Mar. 2, 1920.

4 SHEETSSHEET I.

F. A. UMSTED. PURIFYING METHOD AND APPARATUS FOR GAS MANUFACTURING;

' APPLICATION FILED F EB. 1. 191a.

mama, Patented Mar. 2,1920.

4 snmwsnen 2.

F. A. UIVISTED. PURIFYING METHOD AND 'APPARATUS FOR GAS MANUFACTURING.

" APPLICATION FIL ED FEB. I, I918. 1,332,529, Patented Mar. 2, .1920.

4 SHEETS*SHEET 3.

- 6 15 26"0 I 5, 221 O7 22a -221 v 221 o I I F. A. UMSTED. I PURIFYING METHOD AND APPARATUS FOR GAS MANUFACTURING.

APPLICATION FILED FEB. 1, 1918.

Patented Mar. 2, 1920-,

4 SHEETS-SHEET 4.

III

NFKES; (/7

FRANKLIN A. UMSTED, OF CHICAGO, ILLINOIS.

PURIFYINQMETHOD AND APPARATUS rorv GAS-MANUFACTURING.

.useful Improvements in Purifying Methods and Apparatus for Gas-Manufacturing, of which the following is a specification.

My invention relates to improvements in low temperature, dry distillation method of manufacturing illuminating, power and industrial gas. and obtaining all of the valuable by-products therefrom together with the improved apparatus for carrying on the manufacture of same.

7 The'primary object of the invention is the provision of a method and improved apparatus for carrying out the method by which I-am enabled to utilize waste materials such as garbage, manure, street sweepings, municipal waste such as sewage, peat, saw dust, waste wood. stumps, lignite, low grade sulfurous coals, sugar mill waste, sugar refinery waste, beet and cane sugar pulps and stalks, corn stalks, alfalfa, (green or dry). packing house waste, both "animal and vegetable, and in fact any animal or vegetable substances containing sufficient moisture base to give gas upon proper application of heat.

It is a further object of the invention to secure in alrimproved method and apparatus of the described character greater economy and elliciency in the production of gas and lay-products utilizing standard gas making fuels by which I mean the fuels ordinarily employed in the manufacture of lighting and heating gases as well as the .materials heretofore referred to.

Other'objects of the invention will appear from the following specification which is directed to the preferred embodiment of the invention, the apparatus preferred to be used being depicited in the accompanying drawings of which Figure 1 is a perspective View of a complete system. embodying the im proved apparatus of the invention. Fig. 2 is a vertical cross sectional view through the retort and regenerating furnace. Figs. 3 to 6 inclusive illustrate my improved purifying apparatus, Fig. 3 being a broken top plan view and Fig. l a broken end elevation, while the interior arrangement of the purifier is shown in detail in Figs. and 6, which taken'together illustrate a longitudinal vertical sectional view through the puri Specification of Letters Patent.

Patented Mar. 2, 192(1).

Application filed February 1. 1918. Serial No. 214.863.

fying apparatus. Fig. 7 is a sectional view illustrating the details of construction of the cooling temperature reducing tank.

In the complete system view Fig. 1, the retort is designated generally by the reference character 10; the purifying apparatus is designated generally by the reference character d0; designates a compressor; a cooling temperature reducing tank. 80 is an acid treating tank, 90 is a second compressor and the reference character 100 is applied generally to indicate the final storage gas holder. Before entering upon a detail description of the various units of the system beginning with the retort, it should be stated that the material to be treated for the production of gas and by-products is to be placed in the chamber 11 of the retort 10, in which it is subjected to a gas producing heat but of 'a somewhat lower temperature than ordinarily employed in the production of gas. The heat in my improy'ed retort is applied to the outside of the heat chamber only and does not come in direct contact with the material being treated in the retort chamber. pipes or passageways between the units of the system it will be noted that I have followed the approved practice in gas engineering of employing right angular passages where angles are necessary in preference to the curved passages, as it is well known that curved passages tend to clog or collect by-products and sediments. Another advantage of the angular type of connections is that ready access is afforded to angles and connections for the purpose of readily cleaning the pipes and connections.

This treatment in the purifying device will;

be described in detail in connection with the consideration of the details of the puri fier, it being sufiicient to state in the present brief description that in the purifier certain of the by-products will be precipitated in the various compartments of the purifier to be subsequently drawn off while the as upon leaving the purifier is now in a; per ect In the details of the connecting a I aeasaa state of purification for illuminating purposes. To those skilled in the art it will be understood that I mean by this that the gas is in a state of purification upon leaving the purifier that fits it for maximum efficiency as an illuminant although obviously as is well known illuminating gas contains other valuable by-products which I treat in subsequent portions of the present apparatus to be described.

The purified illuminating gas leaves the purifier l0 through the tubular connecting portions 55, 56, 57, 58, passing thence to the power operated compressor 60, which is of any usual type of construct-ion and is illustrated only diagrammatically in Fig. 1, the power wheel of the compressor being designated by the reference character 61 in the compressor 60. The gas is placed under a higher degree of pressure upon leaving through the duct 62 and passes thence through connections 63, 6-iand 65 to. the temperature reducing tank 70, where it enters the bottom of this tank through the inlet pipe 65. the outlet of which is raised a sufficient distance above the bottom of the tank to prevent interference with accumu lated by-products therein. The tank is preferably .of the ordinary construction of sectional lift water seal tank as shown in detail in sectional view Fig. '7. In the cooling tank 70 the compressed gas of illuminating qualities before stated is subjected to the action of the cooling fluids which are contained in closed pipes so that the cooling n edium does not come in direct contact with the gas. In cooling tank 70 certain remaining by-products are deposited due to the chilling of the gas upon coming in contact with the cooling tubes. The gaseous portions of the fluid pass thence through ducts 66', 67, 68, 69.71, '72, 73 and 71 to the reheating chamber or retort 75, which is a closed chamber'inclosed within the structure of the retort as shown in Figs. 1 and 2, being so arranged therein as to utilize waste heat currents passing from the fire box surrounding the generating chamber or retort 11. The normal course of the gas after expanded by heat in the reheating chamber 7 5 is through ducts 7 6. 7 7 and 78 into .the acid treating tank 80. The latter may be of the general form shown in Fig. 1 divided into compartments in such a manner that all gas entering therein will of necessity pass through an acid bath composed of such acids as will remove all of the remaining 'by-products that are contained in 'the gas. ofthe tank 80 is divided into'two compartments by the plate 81 which projects from the top of the compartment down.-

.wardly a short distance from actual contact witlrthc bottom but below normal level ofthe acid fluid contained within the tank;

For example the form,

thus the acid bath will furnishe liquid seal between the compartments and all gas passing through the inlet duct 78 into the first compartment will pass through the acid bath beneath the plate 81 into the exit chamber, leaving the gas in the state of highest efliciency in British thermaT'or heat units and 'adapted' for use for industrial and power purposes. By this Imean that at this stage the gas is a fixed or permanent gas and suited for storage orcompression in that it will no longer precipitate liquids upon cooling but will remain indefinitely in a dry fluid state and will remain in storage permanently in such condition, also making it'in this state suitable for shipment or transportation or storage in portable containers.

The acid bath is designated in the tank by the reference character 82. The -prepipe 93 shown as having its :outlet some distance above the bottom of the tank to as sist in the normal circulation of the gas within the final storageholder, the latter being indicated by the reference character 100. and being shownin 1 as of the ordinary form of water seal sectional gas holder. From the final storage holder 100 the gas will be taken as desired for purposes of distribution as through the outlet duct 91. 95.

Obviously the finalstorage holder may be dispensed with underconditions where it is possible to utilize the gas as fast as produced and coming from the, final compressor 90. For example under some conditions a plant of the described character. may be utilized to supplement the production of other gas' plants or supply mains in which event the gas may be piped directly from the final compressor 90 into such gas mains.

It will be apparent fromthe above description. of my invention that everything taken from the gas after it leaves the purifier 40 will be at the expense of its illuminating qualities. Under some conditions it may be desirable to store or consume the gas in its maximum efficiency as an illumi nant in which case I provide the supplementary duct leading directly to the second compressor 90 by tapping int-o the main supply duct 81 between the acid bath tank 80 and the compressor through which the gas may be shunted around the cooling tank and the reheating and acid bath igesaeee apparatus, passing directly into the final storage tank thus avoiding the cooling tank and any precipitation that may take place therein, and also avoiding the reheating and acid bath treatments. ,The duct 110 is controlled by the valve 111. I also provide another cutoff by which the gas upon leaving the reheating chamber may be shunted around the acid bath compartment 80. This consists of duct 112, leaving the pipe 7 6 between the reheating chamber and the bath chamber and tapping into the duct 84 between the bath chamber and the second compressor. This supplementary duct is under the control of valve 113, and enables the gas after being reheated to be passed directly through the last compressor and storage holder avoiding the acid bath for the'purpose of supplying a gas that is suitable for general domestic purposes,

that is, leaving sufficient illuminants in the gas to enable it to be used with a fair degree of satisfaction for illuminating purposes, but at the same time retaining, the heat energy of the gas for domestic heating or power or industrial purposes.

In carrying out my improved method of manufacturing 'gas and removing and conserving the valuable byproducts therefrom I find it essential to employ certain of the units of myimproved apparatus as herein described, including the special retorting furnace,.the improved purifier, and the improved temperature reducing tank. Before referring more particularly to the method of manufacturing gas the more important units of the apparatus will be described.

I Tlze generating (and reheating furnace.

The generating furnace or retort and the reheating furnace are preferably combined in the manner illustrated in the perspective view and in the section through this com-' bined apparatus, Fig. 2. Reference has already been made to the closed metallic retort 11 of elongated. form having a curved top and sides and a fiat bottom and surrounded by a fire chamber on the interior of the walls 10 of the furnace proper which may be of brick or other masonry'as shownin Figs. 1 and 2. .The retort chamber 11 is permanently closed or sealed throughout except at the feeding end projecting through the outer wall of the furnace and being provided with :the removable or detachable member or door 11' pivotally connected with the supporting member or arm .11, which latter is pivoted to the wall of the retort chamber adjacent the mouth thereof as indicated at 11. The door may be closed in position to seal the end of the retort 11 by pivoted keeper or clamp 11 adapted to engage with the free end of the supporting lever 11*. and being provided with the screw clamp 11 adapted to engage the freeend 11 of the door sap retort chamber.

port and pressthe supporting dever 11 toward the opening of the chamber in such a manner as to cause the door 11 to seal the end of the retort chamber whenever it is filled with material adapted to be retorted or reduced to a gaseous condition.

I prefer to construct the retort chamber in such a manner that the fire'chamber therein may surround practically the entire body of the retort 11, the latter being supported however at its ends in the front wall of the masonry furnace 10, and also in the rear wall not shown in the drawings. The retorting fire chamber is indicated by the reference character 1, Fig. 2, and the grate bars therein by the reference character 2. The

bottom of the firing chamber below the grate is preferably closed by the pan or bottom member 3. There are doors 4 and 5 closing passage ways through the walls of the furnace, these passage ways extending at right angles to the longitudinal diameter of the retort chamber 11.

the furnace beneath the grates and to enable ashes and depositscoming from the grates to be removed. Door 4 closes the ordinary opening for the admission of fuel, and this is also supported near its ends so as to be surrounded by the supplemental walls of the furnacesurrounding same. The latter is not provided with grates since this sup plemental heating chamber is designed to utilize waste heat currents coming fromthe The latter of these pa'ssage ways is designed to afford a draft to generating or retorting furnace 1. This is-- accomplished by providing one or more ducts 7, 8, and 9 leading out of the retort chamber 1 to a common tortuous passage a, communicating with the three openings 7, 8 and 9, and leading through the communicating passage 6 into the top of the Y chamber 6 around cylindrical reheating chamber 75. The opening 6 surrounding the reheating chamber 75 communicates with the vertical flue c in the chimney associated with the retorting and reheating furnace 10, this chinmey being of. the desired height to conduct away the products of combustion within the firing chamber of the retort and reheating furnace, and to furnish the desired draft to properly operate the apparatus. By arranging the fuel door 4 at the; side of the rrt furnace and on account of the damper controls (I and e for controlling the elongated passage ways around the curved sides of the retort 11, and the damper controls f, g and h in the passages 7, 8 and 9 leading from the retort firing chamber 1, I am enabled to utilize the fuel within the retort chamber to the limit of economy. For

' Way a b' and the reheating chamber and the chimney of the retort plant. If less efliciency is desired from'the fuel under the conditions last mentioned the closing of the damper cont-r01 e and the opening of the control (Z will cause the fuel draft to traverse only a comparatively short part of the exterior surface of the retort chamber 1-1 in passing through the outlets f, a and b to the reheating chamber and chimney thus greatly reducing'the efliciency to be obtained from a given quantity of fuel.

The purifying apparatus.

The reference character 40 is applied generally to indicate the purifying apparatus as shown in the system viewFig 1, the details of this unit being illustrated in Figs 3 to 6 inclusive The purifying apparatus consists of a casing of a size to be determined by the capacity of the plant and preferably of substantially the configuration shown in Figs. 3 to 6 inclusive, in which the casing is rectangular in cross section and provided with a plurality of partitions preferably 9 in all dividing the easing into 10 intercommunicating chambers all of which are preferably closed to the outside atmosphere. These chambers are designated generally by the reference characters 201 to 210 inclusive, reference characters 201 and 210 being applied to the'end chambers of the purifien' These end chambers of the purifier compartment are provided near their upper extremities with the inlet and outlet manifolds 211, 212 respectively, the former being adapted to receive the supply main or.

duct 13 leading from the retort of the generating furnace. while the outlet manifold 212 communicating with the chamber 210 furnishes a convenient means for the attachment of the discharge main or ducts 55, 56 leading to the first compressor 60, or through theshunt pipe direct to the second compressor of the system. 'T he 10 chambers of the purifier may be of substantially the same size and dimensions as illustrated in the drawings and I prefer to a-rrangeeach of the 10 chambers of the purifier with openings in their tops closed by the removal cover there being openings shown through the bottom wall of the purifier casing as shown in Figs. 5 and 6, said openings being closed by plates 215 provided with screw threaded openings for taking the vertically and downwardly extending drawoif pipes or tubes 216, which are screw threaded for engagement with the plates 215. The drawofl" pipes 216 are controlledby suitable interposed valve casings 217, having gate 1 valves or other convenient forms of closure members therein and operable from the exterior as indicated at 218-, Fig. 4. The purifier casing is 'divided into the cgmpartments 201' to 210 respectively by division plates ofmodified construction to adapt the respective compartments for the various functions they are called upon to perform in the operation of purifying the gas passing therethrough. Arranged within the chambers 201 to 205 inclusive and 210 and extending laterally therethrough from side wall to' side wall of the purifier casing proper are a. pluralityof tubular passages 219 beingsecured at their extremities in the end walls of the casing so that they afi'ord open passage ways for cooling fluids such as cold air for example passing from the air intake manifolds 220 to the exhaust air manifolds 221 on the opposite side of the purifier casing common to each of the chambers 201 to 205 inclusive and 210 provided with the said tubular passages.- Since chambers 206 to- 209 inclusive are not provided with the laterally extending tubular passage ways they are not provided with the intake or exhaust manifolds. While many circulating cooling fluids may be used in operating my improved purifying apparatus, I prefer for economy and eificiency to use cold air which may be taken from the exterior of the building in which the purifier is installed as illustrated in Figs. 3 and 4 in Lssacae pipes or they may usually operate as chimneys, theheated condition of the gases undergoing purification being suflicient to maintain a circulatory draft in the desired direction through the purifying apparatus.

The process and method of operating the system- The material to be retorted is placed in the chamber 11 of the generator or retort and the removable closure or door 11 is secured in position to hermetically seal the re tort except for the outlet pipe 13. Fuel is then introduced in the fire box 1 of the retort through the fuel door 1,, to heat the retort and the dry distillation begins. It is an important feature of my improved method that from the time vthat the mate rials are retorted until the purified ga s -is deposited in the final storage holder 100, there is a complete absence of the introduction of moisture in the form of water or vapor to be co-mingled with the gas producing materials or gases generated therefrom in the system. ,Fo-r example it is the common practice in retorting in the manufacture of gas to introduce large quantities of water or vapor into the retort chamber itself and to force the gas through purifiers or scrubbers by jets of moisture in the form of steam all of which is carefully avoided in my improved method and apparatus. The prevailing practice in gas manufacturing is to retort the material co-mingled with moisture or water at a temperature at ap proximately 2200 to 2800 degrees (Fahrz) This results in the prevailing practice of the use of an abnormally large quantity of fuel to attain the desired temperature for retorting and furthermore such temperatures are unduly destructive resulting in the loss of a large percentage of the material being retorted, whereas in my improved process I prefer to employ temperatures varying from 4100 to 600 degrees as the minimum up to 1200 degrees Fahr. as the extreme maximum, according to the quantity of the material being retorted, and in the utilization of such comparatively low temperatures I save a large percentage of the gas generated at the same t me securing a thorough degree of distillation because of he fact that water or other moistures are kept out of the retort.

I also find by careful tests that by my method of dry distillation in the retort I am enabled to distil with about -}of the heat units ordinarily required by any other known method of retorti'ng, thereby conserving more than 50 per cent. of the usual fuel requirements. The as upon being generated and driven from t e retort due to the expansion in the retort enters chamber 201 of the purifier through the header 211 near the top of .the chamber at a temperature above 390 degrees Fahr. Passing thence downwardly through the compartment the gas contacts with the exposed surfaces of the cooling plpes 219 in the compartment 201 there being a draft of a cooling fluid passing through these pipes from the intake header 220 to the exhaust header 221. The draft through these headers and the cooling plpes 219 of the compartments of the purifier provided with such cooling pipes may be obtained by the draft lines 223 connected with the exhaust headers 221 or through other suitable draft inducing devices such as suction pumps and the like. The provision by which the intake of the manifolds 220 is on the exterior of the building ordinarilyinsures the introduction of cold air through the coolin tubes while heat given ofi in the cooling tubes will tend to rise through draft flues or pipes 223 tending to induce circulation through the cooling flues in the direction indicated by the arrows in Fig. 3. The

compartment 201 is without any packing materials or other devices beside the cooling tubes 219 and as the gas contacts with the chilled surface of these tubes in its downward passage through the compartment there results the condensation and removal from the gas of tar or other heavy byproducts such as phenols which will accumulate upon the pipes and be deposited upon the bottom. of the compartment to be subsequently drained through the bottom plate 215 and the discharge pipe 216 controlled by gate valve 217. The non-condensed and non-.

be collected upon the bottom plate 215 to be discharged through the valve and discharge pipes connected therewith as in the case of compartment 201.

Unprecipitated gas will rise to the top of compartment 202-(and at a temperature of approximately 175|- degrees to"200[ degrees (Fahn), and pass over the top ofthe; plate between compartments 202 and 203 into the latter compartment, the opening being designated by the reference character 233, Fig.- 5. The compartment 203 is constructed similar to the two preceding compartments, being provided with the staggered cooling pipes 219, and as the gas passes downwardly over the cooling surfaces 'of these pipes medium oils such as turpentine light pitch and kindred products will be condensed and precipitated to be removed from the bottom discharge at pipe 216 as desired. The compartment 203 contains no packing or filtering material aside from the cooling tubes 219. The compartment 203 is divided from the compartment 204 by division plate 234 havingthe opening 235 near the bottom thereof and through which the gas passes from compartment 203 at a temperature at approximately 140+ degrees to 160+ degrees (Fahn) into compartment 204.

Compartment 204 is the first of the con-- secutive compartments provided with packing material. Like the receding compartments it is provided with a plurality of transverse cooling pipes 219 preferably 11.

in all in staggard relation but somewhat more separated, there being three less pipes compartments 201 to 203 inclusive. compartment is separated from compart- -ment 205 by the division plate 236 affordin this compartment than in the preceding This ing a passage way over the top side of the plate into the compartment 205 so that the gas upon entering the compartment 204 near the bottom through opening 235 will traverse the length of the compartmentpassing through a packing of water condensate materlals such .as coke, charcoal, lnne -or sawdust for the purpose of absorbingand removing water therefrom. Condensation and precipitation of moisture will he obviously expedited by contact also with the surfaces of the air cooled pipes 219. The condensate materials with which this compartment is packed are supported just above the bottom plate 215 to prevent clogging the outlet duct 216 by suitable screen as indicated at 237. After traversing the vertical length of the compartment 204 the gas will pass through the opening at thetop of division plate 236 indicated at 238 and will enter the top of compartment 205v at a temperature of approximately 104+ degrees to 114+ degrees, (Fahr.) This compartment contains a still lesser number of cooling tubes 219, 9 in all arranged transversely of the compartment between the inlet and outlet manifolds. The division plate 239 dividing the compartment 205 from its succeeding'compartment 206 is provided with an outlet 240 near the bottom so that the gas on entering this compartment at the top traverses the length of the compartment, striking the cooling tubes 219, which latter are submerged in a mixture consisting of equal parts of oxid of iron and sawdust, the oxid of iron being in small granules and the wood being pulverized or in the form' of sawdust for the purpose of removing from the 'gas passing therethrough heavy or concentrated ammonia and kindred products. In this compartment there is a screen arranged some distance above the bottom plate 241 for the purpose of holding the purifying materials consisting ofoxid of iron and sawdust from mixing withammonia and kindred products precipitated in this chamber and enabling the precipitations to be drawn off without disturbing the packing material. The free gasleaves the compartment 205 through the opening 240 at a temperature at approximately 98+ degrees to 104+ degrees (Fahiz), entering compartment 206 near the bottom thereof. This compartment is divided from the. succeeding compartment 207 by the double wall the first part of which is indicated at 242, and is provided with an opening 243 at the top affording a passage way between this plate 242 and the plate 244 between compartments 206 and 207. This passage way opens at the bottom beneath plate 244 into the compartment 207.

In order to simplify the description it may be stated that the remaining compartments 207, 208, 209, 210 respectively are interconnected in the same manner as the compartments 206 and 207by the staggered plates alternately securedat the bottoms and tops of the compartments and affording downwardly extending passages between the respective compartments. These staggered walls being indicated by the reference characters 245, 246, 247, 248, 249 and 250. The intake into each respective comparunent as is the case with compartment 207 being at or near the bottom of the compartment and the outlet at the top. Each of the compartments 206 to 209 inclusive are provided with screens some inches above. the bottom of the compartments corresponding to the location of the screen 241 of compartment 205, these screens being designated by the reference characters 251 to 254 respectively. Compartment 206 is loaded solid above the screen 251 with wood, sawdust or finely divided wood particles, but the compartment is not provided with the laterally extending cool mg tubes characteristic of compartments,

compartment which is also without cooling tubes, and here the balance of ammonia and kindred products are removed and the drying of the gas begun. The loading in this compartment is preferably a stratum of about one half the space above the screen with pulverized lime succeeded by a-two inch layer of pebble lime which is lim broken into particles about the size of marbles. The remainder of the compartment above the lime stratum consists of charcoal in the form of pellets the size of.

hen eggs for the purpose of removing sulfur and kindred products from the gas as it-v equal mixture of oxid of iron and sawdust to complete the removal of cyanogen and dirt particles. Leaving the compartment 209 at the top the gas at a temperature of approximately 89+ degrees to 92+ degrees (Fahr.) enters the compartment 210 at the bottom thereof. This compartment like the first five compartments of the purifier is provided with a plurality of transverse cooling pipes preferably 9 in all, in staggered relation.

Thiscompartment is provided with a screen almost midway between the top and bot tom thereof so that three of the transverse cooling pipes 219 are comprised in the space below the screen.

The space below the screen is loaded with a solution of heav cream of lime. The next two inches abovet e screen being designated by the reference character 255 is loaded with crushed coke. There is then a layer of two inches of pebbled lime the size of marbles and above this to the top of the compartment 'a stratum of crushed coke about the size of ordinary marbles. The gas passing upwardly through the cream of lime solution will have the remaining moisture therein removed and the contact with the chilled surfaces and tubes surrounded by the layers of coke and lime will remove any moistureremaining in the gas together with the remaining naphthalene, heavy benzol and kindred products. The gas will pass from the compartment 210 into the manifold 212 at an approximate temperature of 58+ degrees to 64-] degrees, (Fahn) From the manifold 212 the gas may be piped as hereinafter described direct to a storage holder or to units for further refining and removing benz-ol and lighter chemical constituents.

It should be noted that each of the. 10 compartments of the purifier is provided with a 'drawoff 216 leading from the bottoms thereof and controlled by the gate valve 217. The precipitates referred to that collect in the bottoms of each of the respective compartments of the purifier will act as a seal for the outlet ducts 216 so that any of these ducts may be opened at and during the operation of the plant and byproducts removed, care being taken to close the valves when gas begins to'esc-ape. An important feature of the invention is an automatic means for controlling the inlet manifolds supplying cooling fluid to the tubes in compartments 201 to 205 inclusive and compartment 210. Referring to the inlet manifold 220 as shown for example in Fig. 4, it will be seen that the intake 220 is adapted to be closed by the damper, 220", the latter being controlled by the reciprocating rod 220, connected through stufling box 220g with a thermostatic regulator, indicated at 220 on the interior of one of the. 00111- partments of the purifier as for example either of compartments 201 to 205 inclusive and compartment 210, each of such compartments being provided with this thermostatic controller for regulating the admission of the cooling'fiu'id. The purpose of this controller is to keep the temperature within the compartment approximately correct in order to insure precipitation of the various byproducts as enumerated in connection with the operation of these compartments. I

Another important regulating and safety appliance consists of the gas pilot light indicated at 260, Fig. 4c. In each of the compartments there is provided a few inches above the bottom plate of the compartment an outlet duct as designated by the reference character 261, Figs. 5 and 6. The ducts 261 communicate with pipes 262 leading to the pilot lights 260 and are for the purpose of furnishing a constant indicator to the attendant or operator that each of the purifying compartments 201 to 210 respectively are operating properly and are not clogged with an oversupply of byproducts in the bottom of the compartments. For example the outlet ducts 261 are all located approximately at the upper limit of the danger line, and when the accumulation of thebyprodnets in any given compartment passes the predetermined limit as fixed by the location .110 of the pilot light duct, the precipitated 3 0?" cumulation of byproducts will clog the outlets'leading to the pilot light 260 and cut off the supply of illuminant from that compartment. Obviously when the purifier is in operation each of the pilot lights comprising the individual compartments or chambers should be in operation and upon failure of any light to burn for the reasons stated the attendant will be notified that the It will be seen from the foregoing description of the purifier unit 40 that the gas undergoing treatment within the conipartments 201 to 210 respectively will be out of contact as before in the retort from all con tact with water or steam resulting in the production by this dry process at the point of exit from the last purifier compartment 210 into the outlet manifold 212 of a gas of the highest illuminating quality. It is well known to those skilled in the art that while gas purified to the degree herein before described in the 10 compartments or chambers of the purifier, is of the highest illuminating acter 70, and shown in greater detail in sec tional-view Fig. 7. A suitable power operated compressor is interposed in the piping system between the purifier 40 and the tem perature reducing tank 70. The course of the gas upon leaving the discharge manifold 212 of the purifier is through the mains 55 to 58 inclusive to the compressor 60 and i from thecompressor through the mains 62 to 65 inclusive discharging thence into the interiorof the cooling tank 70. This tank may be of the common type of water seal storage tank, modified however with respect to the provision of a special system of cooling pipes in the form of spiral coils as indicated by the reference character 300, the coils of the pipe 300 being supported by the spaced depending members 301, 302 as shown in Fig.7 arranged to take the pipe coils 300 between them, the coils being sus- P pended by the connecting straps 303. A suitable cooling fluid as brine is circulated through the coils 300 entering the topmost coil of the series through the intake pipe or duct 304 which is connected with the top coil of the series by a flexible tubular connection consisting of the hinge jointed pipe sections 3053, 306 respectively. The cooling coil 300 supported by the straps 301, 302, 303 which latter are preferably attached to the movable telescoping section of the tank, is thus adapted to present the considerable cooling surfaces of the coil to the gas with- V in the tank and the circulation of the cooling fluid within the coil is made continuous by the hinged pipe connections leading from the lower loop of the coil to the coil'308 which is distributed over the major part of the tank bottom and lies close upon the said bottom serving to cool precipitated byproducts within the tank to be removed therein from the gas as it is delivered to the tank 7 0 from the purifier 40 through the compressor 60. The last said flexible connection leading from the coil 300 consists of the hinged pipe connections 307, 307 of Fig. 7 which latter is connected through the-bottom of the cooling tank with the discharge pipe 309 from the tank. The movable section of the tank carrying the coolingcoil may be of the single unit construction shown .inFig. 7, or may be made of a plurality of telescoping sections water sealed with the upper section carrying the cooling devices to insure cooling always at the top of the tank. In Fig. 7 the movable section is designated generally by the reference character 7 0 The gas upon being delivered from compressor 60 to tank 70 will be chilled and cooled by the apparatus described so that there will be a considerable precipitation of. oil and benzol which will accumulate upon the bottom of the tank adjacent the coil 308' whence it may be drawn off through the discharge pipe 3l0 shown in Fig. 7. The discharge end of the inlet pipe 65 is shown elevated a sufiicient distance above the bottom of the tank 7 0 to prevent the possibility of overflow and stoppage of the inlet by the rise of accumulations of the precipitates in the tank. The same is true of the outlet pipe 66 which communicateswith the pipe sections 67, 68, 69, 71, 72, 73 and 74 with the reheating chamber 75 within the retort unit 10 already referred to.

A final storage tank 100 ultimately receives the gas for distribution and use as it comes from the system and a power operated compressor shown diagramatically' in.

Fig. l and indicated by the reference character is adapted to discharge the purified gas of the desired quality through the pipe sections 91,92 and 93 into the final storage holder 100. The gas entering the final storage holder may be of several different qualities a cording to the manner in which the system between the purifier 40 and the storage holder 100 is manipulated. For example if it be desired to store gas of the highest illuminating standard or quality as it comes for example fromthe purifier 40 the bypass main 110 will 'be opened by manipulation of the valve 111 adjacent the purifier shunting the. gas directly to the second compressor 90 and thence to storage tank 100 to be distributed as may be desired through the mains 94 95. Under such conditions when the valve 111 is opened the compressor 60 should not" be operated thus closing main leading to cooling tank 70 and also cutting out the reheating chamber 75 and the acid bath treating tank 80 from the system. i

When it is desired, however, to cool and further refine the gas removing the remaining benzol and oils such as nitro-benzene and dinitro-benzene as'byproducts it is necessar to pass the gas from cooling tank throug the reheating chamber 7 5 where the gas is I expanded by the waste heat from the generating chamber of the retort putting the gas in condition for the roduction and removal of the nitro and dimtro-benzenes, before being passed through the acid bath of tank80.

The structure of the tank 80 has been described and from which it ,will be seen that before the gas passes through this tank it will encounter the nitric acid bath, removing the heaviest oils and reases including nitro- -benzene and dinitroenzene which will accumulate upon the top surface of the acid bathwithin the tank. I prefer to provide discharge pipes in the bottoms of each of the compartments in the bath tank 80, these pipes having their intake ends slightly above the normal level of the bath solution. and

outlets at normal level of acid so that accumulating oils and greases maybe siphoned from the tank. This is one of the common methods of removing accumulations in acid treating tanks and the discharge pipes are not shown in the tank 80 illustrated in "Fig; 1. The gas after being reheated in chamber 7 5 andpassed through the acid bath oftank 80 will be of the quality of theordinary power and industrial gas now being furnished in the larger cities for lighting purposes, but on account of being so thoroughly treated and robbed of its byproducts "and illuminants it is only satisfactory for light-. ing purposes when used with mantles. Such 3 gas however is obviously efficient for all power and industrial purposes including all heating purposes and uses in explosive motois- In addition to .the advantages resulting from the use of my improved method and apparatus such as the employment of ex-.- tremely low temperature, thus saving fuel torting at low temperatures stated is found to result in a saving of about one third of the heat units required by other known methods of retorting and the further absence of the usual introduction of large quantities of water into the system either in the form of liquid or steam,'enabling me to conserve a large'percentage of the byproducts as well as the explosive or illuminating gases usually destroyed or absorbed by the prevailing methods employing high temperatures and moisture in distillation and refining. Experiments have demonstrated that I save in or steam in large quantities.

' my reheating furnace alone by the utilizawhich results when the opening to the firing chamber for the introduction of fuel is im mediately below the closure for the retort, as it is obvious that upon the opening of the retort gas remaining therein may be ignited upon the opening .of the furnace door often with disastrous results due to explosions'or fires thus ignited. r

I have found that with the improved system as herein shown and described, after the system is in operation and after the generation 0f the gas has begun in the retort and lias'spread to the various. units of the system, fuel gas for operating the retort furnace may be takenfrom the supply tank 100 for operation of the retort and that the system will then operate on somewhat less than one fourth of the gas normally 'produced by the system, leaving over three fourths of the original gas production to reremain in storage or to be utilized for commercial purposes and: this in addition to the valuable byproducts obtained from the various units of the system as described.

Another advantage ofjmy system is in the use of the nitric acid bath in the place .75 to the elimination of danger of explosion of the common sulfuric acid, since the sul- I.

furic acid not only detracts from the quality and. quantity of the benzol and'kindred oils such as the nitrb-benzene and the dinitro benzene, but it results in detracting from the British thermel heat units of the gas,

thus insuring both its lighting and heating values. The nitric acid bath as employed in my system reclaims the benzol and ex plosives enumerated without the objection stated. p

' Repeated experiments with my improved process and apparatus demonstrate that the dry process employed results in the production of a permanent fixed gas eliminating 4 the usual 8 to 12% loss by condensation, which is wasted in the gas mains by common manufacturing methods employing moisture The U. S. Government statistics show that the loss by condensation of water manufactured gas is approximately from 8 to 12%. It is an important feature at my improved apparatus and process that the plants may be economically constructed in small units adapted for individual use as on farms or inconnectiou with small institutions, thus enabling garbage, sewage and other waste products to be reclaimed and made available for light, heat and power purposes.

I claim:

1. An apparatus for the manufacture of gas embodying a compartment normally closed to atmosphere, said compartment being divided into a plurality of chambers with intercommunicating tortuous passages between the adjacent chambers, certain of said chambers of the closed compartment having cooling pipes extending laterally between the side walls of the compartment and alfording means for the circulation of a cooling fluid through the chambers of the compartments out of contact with gas'undergoing purification within the respective chambers, other of said chambers of the and an inlet for its contiguous compartment,

the said openings between the compartments being alternately arranged near the top or bottom plates of the compartment whereby the inlet and outlet of each individual chamber will be spaced apart substantially the' vertical height of the compartment.

3. An apparatus for use in manufacturing gas embodying a compartment closed to the atmosphere, inlet and outlet pipes for conducting gas to and from the compartment, spaced partitions dividing the said compartment into a plurality of intercommunicating chambers, cooling tubes for permitting the passage of cooling fluid through the chambers of the said compartment out of contact withthe gas therein, drawofi pipes connected with each individual chamber of the compartment for the purposeof drawing ofi' pre cipitates from the respective chambers, and means for indicating on the exterior of the compartment when the accumulated byproducts in the particular chamber should be withdraw to maintain the normal operative condition of the apparatus against clogging.

4. An apparatus for use in manufacturing gas embodying a compartment closed to the atmosphere, inlet and outlet pipes conducting gas to and from the compartment, spaced partitions dividing the said compartment into a plurality of mtercommunicating chambers, cooling tubes for permitting the passage of coolingfluid through the chambers of the said compartment out of contact with the gas therein, drawofi' pipes connected with each individual chamber of the compartment for the purpose of' drawing ofi' precipitates from the respective chambers, and a signaling device to indicate on the exterior of the compartment when the accumulated byproducts in any of the chambers of the compartment have reached a predetermined level that might interfere with the operation of the apparatus, said means comprising an outlet duct or pipe tapped into the wall of each of the chambers of the compartment at the predetermined vertical limit for byproduct accumulations in the chamber bottoms.

5. An apparatus for the-purification of gas embodying a closed compartment, there being inlet and outlet passages for gas at the opposite ends of said compartment near the top of the compartment, a plurality of spaced partitions dividing the compartment into a plurality of interoommunicating chambers, the end chambers of the series being connected with the inlet and outlet passages, there being openings in thedivision! plates between the chambers of the compart-\ ment, said openings being in staggered relation so that the inlet to each of the chambers of the compartment is near the end of the chamber which is opposite to the end of the compartment near which-the outlet is 10- cated, and means for introducing a cooling fluid out of contact with the gas in the compartment into a plurality of the chambers of the compartment.

' 6. In a purifying apparatus for gas the combination with a closed compartment, of inlet and outlet ducts for permitting the circulation of gas through the compartment, me'answithin the compartment for permitting the circulatidn of cooling fluid through the compartment, the said cooling fluid to be maintained out of contact with gas within the compartment, there being a plurality of intercommuni'oating chambers in the compartment each of said chambers having spaces at their bottoms for the accumulation of byproducts resulting from the purification of gas, means for draining the said byproducts accumulating spaces, and signaling devices for indicating the height of byproduct accumulations in the respective chambers of the compartment, comprising tubes tapped into the walls of the compartment and communicating with each individual chamber, and lighting devices connected with each of said tubes.-

7. In an apparatus for the purification of gas the combination with a closed compartment having inlet and outlet gas passages, division plates for dividing the said compartment intoia plurality of intercommunieating chambers, there being openings substantially the length of the chamber, and

means for drawing byproducts from each of the said chambers. g

8. In a purifying apparatus for usefinithe manufacture of gas the combination with'a closed compartment provided with inlet and outlet openings, a plurality of intercommunicating chambers within the compartment, means for introducing cooling fluid into the said chambers out of contact with gas on the interior of the chamber for the purpose of providing cooling surfaces for chilling the gas, means for supplying a cooling fluid, and a thermostatic or heat operated device for controlling the admission of cooling fluid to the said cooling devices .of each of the respective chambers of the compartment.

9. In a purifying device for use in the manufacture of gas, the combination with a cooling chamber of a cooling tube extending through said chamber out of contact with gas contained on the interior of the chamber, means for supplying cooling fluid to the said cooling tube, and. a thermostatically or heat operated device for controlling the circulation of cooling fluid to the said cooling tube.

10. In a purifying device for use in the manufacture of gasthe combination with a closed compartmentof substantially rectangular form being divided into a plurality of intercommunicating chambers by spaced partitions, the said spaced partitions having openings so positioned that the outlet to each of the chambers of the compartment is at substantially the end of the chamber opposite to the end at which the intake opening to the said chamber is located, valve controlled drawoff pipes connected with the bottom parts of the chambers of the said compartment, and removable closure plates for the tops of each of the respective chambers of the compartment.

11. In a'purifying apparatus for use in the manufacture of gas, the combination of a substantially rectangular compartment divided into a plurality of inter-communicating chambers, valve controlled drawofl pipes for each of said chambers, cooling pipes passing through the chambers of sald compartment and being adapted to circulate cooling fluid through said compartment out of contact with gas contained therein in order to present chilled surfaces 1n contact with the gas in the compartments, an inlet manifold communicating .with the cooling tubes of each individual chamber of the compartment provided with said tubes, means for controlling the admission of cooling fluid into said inlet manifolds, exhaust mani folds communicating with each of the said chambers of the compartment as are pro- Vided with the said cooling tubes and inlet manifolds therefor, and means connected with said outlet manifolds for exhausting the cooling fluid therefrom and inducing a circulation of cooling fluid through said manifolds and cooling tubes. p

12. A purifying apparatus for use in the manufacture of gas comprising a closed compartment, a plurality of intercommunicating chambers within the said compartment, a portion of said chambers of the compartment being provided with cooling tubes adapted to cause the circulation of a cooling fluid through the respective chambers so provided wlth tubes o'utof contact with gas in the said chambers, other of said chambers of the compartment being loaded with purifying materials,'screens located in said chambers of the compartment loaded with the said purifying material to maintain space in the bottoms of said com partments for use in the accumulation of byproducts resulting from gas purification, and drawofl' pipes valve controlled communicating with the bottoms of the respective chambers of the purifying compartment.

13. A purifying device for use in the manufacture of gas comprising a substantially rectangular compartment divided intoa plurality of intercommunicating chambers, valve controlled drawofl' pipes in the bottoms of each of the said chambers, gas 3 cooling means in certain of said chambers,

gas purifying or filtering means in other of said chambers of the compartment, a chamber within the compartment provided with cooling tubes and loaded with purifying material, and detachable cover plates for the tops of the respective chambers of the puri- Jfying compartment.

let. In a purifying device for use in he manufacture of gas the combination with a closed compartment divided into a, plurality of intercommunicating chambers, cooling tubes passing laterally between said walls of said chambers for the purpose'of permitting the circulation of cooling fluid through the said chambers out of contact with gas on the interior of the chambers for the purpose of precipitating byproducts from the gas to the bottoms of said chambers, and a pilot or warning light connected with the inside of one wall of each compartment adjacent the lowermost of the said cooling tubes within the compartment.

15. In a purifying device for use in the loo manufacture of gas the combination with a closed compartment being dividedinto a plurality of communicating chambers, of cooling tubes connected with certain of said chambers being adapted to present cooling fluids to the interior of said chambers out of contact with the gas contained therein, means for supplying cooling fluid to the said cooling tubes, a thermostatic regulator on the interior of each of said chambers and connections between said thermostatic regulators and said cooling fluid supply.

16. In a purifying device for use in the manufacture of gas the combination with a closed compartment provided with opposed inlet and outlet passages, a plurality of intercommunicating chambers within the said compartment arran ed in series between said inlet and outlet passages, cooling and filtering devices for precipitating byprod-' ucts from the gas within said intercoinmumeating chambers, valve controlled drawofi" pipes in the bottoms of each of the respective chambers, closure plates in the tops of the respective chambers, and screw threaded closure plugs for temporary access to the interiors of the said chambers located in the said top closure plates.

17. The herein described method of re-.

moving by-products from gases which consists in passing gas at a temperature of approximately 390 degrees to 455 degrees Fahr.

through a chamber having a plurality of transverse containers or tubes therein open to the-exterior of the chamber and closed to the gas therein, the said tubes or containers having a' cooling fluid circulated therethrough and also out of contact with the gas within the chamber for the purpose of precipitating the heavy by-products as tar and phenols, then passin the gas and non-precipitated materials into a second chamber also having a plurality of tubular containers closed to the gas and open to the circulation of a cooling fluid out of contact with the gas in the container whereby the gas at ,a

. will be caused to precipitate medium oils as turpentine and light pitch, then passing the remaining gas and non-precipitated materials into a fourth chamber at a temperature of approximately 140 to 160 degrees Fahn,

the said fourth chamber being packedw'ith water condensate materials as coke, charcoal,

lime and sawdust for the purpose of precipitating and removing moisture from the gas, then passing the gas into a fifth chamber at a temperature of approximately 104 degrees to 114 degrees Fahn, the said chamber being packed with dry oXid of iron and sawdust for the purpose of removing ammonia, heavy benzol and kindred products from the gas, then passing the remaining gas and non precipitated materials into a sixth chamber at a temperature of approximately 98 degrees to 104; degrees Fahr. which said chamber is packed with finely divided wood particles or sawdust for the purpose of removing lighter ammonia, heavy naphthalene and kindred products, then passing the remaining gas or non-precipitated materials into a seventh chamber at a temperature of approximately 96 degrees to 100 degrees Fahix, the said chamberbeing packed with lime and charcoal for the purpose of precipitating the remainder of the ammonia and kindred products and for further drying the gas, then passing the gasat a temperature of approximately .90 degrees'to 95 degrees Fahr. into an eighth chamber packed with oxid of iron for the purpose of remov ing cyanogen gas and sulfur, then passing the remaining gas and non-precipitated materials into a ninth chamber packed with a mixture of oxid of iron and sawdust to complete the removal of cyanogen and sulfur and any dirt particles remaining in the gas, thenpassing the gas at a temperature of ap proximately 89 degrees to 92 degrees Fahr. into a tenth chamber packed with lime and crushed coke for the purpose of removing the remainder of the moisture in the gas and any remaining naphthalene, heavy benzol or kindred products, then passing the gas from the purifier at a temperature of approximately 58 degrees to 64 degrees-Fahn, the

gas then being a fixed gas, to a storage holder or to other apparatus for further refining.

18. The herein described method of removing by-products from gas which consists in'pa ssing the gas through suitable con-- tainers having tubes'therein closed to the interior of thecontainer said tubes having cooling fluids therein for the purpose of removing by-products as tars, phenols, pitch, heavy oils, turpentine and creosote, then sub mitting the remaining gas and non-precipitated materials to a chamber packed with Water condensate materials as coke, charcoal, lime or sawdust for the purpose of removing moisture from the gas, then passing the gas through a container packed with dry oxid of iron and sawdust for the purpose of 12a removing ammonia, heavy naphthalene and kindred products, then passing the non-precipi'tated gas and remaining materials into a chamber packed with lime and charcoal for the purpose of removing sulfur and kin- 130 bers of the casing spaced from the openings the interior of the same into a plurality of intercommunicating chambers, means for introducing gases to and removing treated gases from the casing, means for collecting and permitting the removal of precipitated materials from the bottoms of the individual chambers Within the casing, there being gas outlets in the walls of each of the said chamin the bottoms of the chambers permitting the removal of the accumulated by-products but so related to the bottoms of the chambers adjacent the by-products discharge openings therein that an abnormal accumulation of by-products within the individual chambers will close the gas outlet in each chamber, and a pilot light or burner c0nnected with each of the said gas outlets for utilizing gas passing therethrough.

20. In a purifying apparatus forremoving byproducts from gas, a casing, a plurality of partitions in the casing dividing the interior of the same into a plurality of intercommunicating bhambers, means ;for introducing to and removing treated gases from the casing, means forcollecting and permitting the removal of precipitated materials from the bottoms of the individual chambers within the casing, there being a gas outlet in the Wall of one of said chambers of the casing spaced from the opening permitting the removal of the accumulated byproducts from the casing, and being so related to the bottom of the chamber that an abnormal. accumulation of byproducts therein will close the gas outlet in the chamber, and a pilot light or burner connected with the said gas outlet for utilizinggas passing therethrough, and whereby the light or burner will reniain burning as long asnormal operation of thechamber is permitted but will extinguish by an accumulation'of byproducts abovethe redetermined positioirof the gas outlet in t e wall of the chamber, I V a 21. In a purifying apparatus for removing byproducts from gas, a casing, a plurality of partitions inthe casing dividing the interior I of same into a plurality of intercommunicating chambers whereby gas entering one of the chambers may pass through the successive chambers in series,

a plurality of transverse tubes in one or more of the chambers adapted to receive the gas at the intake end of the casing,

means for introducing a cooling fluid to the interiors of the said cooling tubes out of contact with the gas in the chambers, the said chambers provided with said tubes being without packing material whereby the gas will contact with the tube surfaces, another chamber in the compartment provided with transverse cooling tubes, the last said chamber having the cooling tubes therein covered with granular filtering material, one or more chambers having a portion thereof filled with granular filtering material through Which the remaining gas is passed for the purpose of cleaning and removing dirt particles, cyanogen gas, sulfur and other impurities, and a final chamber in the casing into which the remaining gas is introduced, the said final chamber being provided with transverse cooling tubes and a loading of lime through which the gas is forced to pass before leaving the casing for the purpose of removing moisture therefrom.

22. In a purifying apparatus for removing byproducts from gas, a casing, a plurality of partitions in the casing dividing the interior of the same into a plurality of intercommunicating chambers, certain of being provided with transverse cooling tubes and packed with filtering material, a plurality of chambers arranged in series following the last said chambers each loaded -with a quantity of granular filtering mate-' rial, the last said chambers being closed against the introduction of cooling fluids, a drying chamber provided with a packing of lime or analogous material for finally drying the gas, and transverse cooling tubes in the last said chamber open to the exterior but closed to the interior of the cham- 23. In a purifying apparatus for removing byproducts from gas, a casing, a plurality of partitions in the casing dividing the interior of the same into a plurality of intercommunicating chambers, certain of said chambers being provided with trans- Verse cooling tubes closed to the gas on the interiors of the chambers and open to the reception of a cooling fluid from the exterior of the casing, there being staggered openings between the said chambers and being provided with transverse cooling tubes and packed with filtering material, a plurality of chambersarranged in series followthe last said chambers being closed against the introduction of cooling fluids, and a drying chamber provided with a packing of lime or analogous material for finally drying the gas.

24. In a purifying apparatus for removing b products from gas, comprising a casing ivided into a plurality of chambers with intercommunicating passages therebetween whereby gas entering one of the end chambers of the casing may pass through -the chambers of the casing in series, transverse coolin tubes in certain of said chambers, said tu es being closed to the interiors of said chambers but open to'the exteriors thereof, where'by gas entering said chambers will be caused to contact with exposed surfaces of said tubes for the urpose of removing byproducts as tars, pitch, heavy oils, turpentine and creosote, one or more Lasaaae chambers in the series being provided with cooling tubes similar to .the cooling tubes in the aforesaid chambers but having the exposed surfaces thereof on the interior covered with filtering material for the purpose of removing moisture from the gas, other chambers arranged in series within the casing provided with granular filtering ma= terial, the last said chambers being closed against the introduction of cooling tubes or cooling fluids therein for the purpose of removing ammonia, heavy naphthalene, cyanogen gas, sulfur and analogous byproducts, and a final chamber packed with lime or other suitable dryingmaterial for drying the gasbefore discharging it vfrom the purifier. A g i v In testimony whereof I have signed my name to this specification on this th day of January, A. D. 1918.

FRANKLIN A. UMSTED. 

